Spectra used in a prior-art wireless communications system are classified into two categories: a licensed spectrum (English: licensed spectrum) and an unlicensed spectrum (English: unlicensed spectrum). Any operator can deploy a device on an unlicensed frequency band, for example, deploying a wireless fidelity (English full name: wireless fidelity, WiFi for short) device on a 2.4 GHz frequency band and a 5 GHz frequency band.
In the prior art, LTE-U carrier information is generally transmitted by using downlink control information (English full name: Downlink Control Information, DCI for short) signaling. However, as user equipments in a wireless communications system increase, if DCI signaling is sent to each user equipment for transmitting LTE-U carrier information, there is an overlarge amount of signaling that needs to be processed in the wireless communications system.